It is known that the hair of many people, because of its general condition or because of repeated exposure to the atmosphere or to treatments such as bleachings, permanent wavings or dyeings, becomes degraded and often difficult to comb out or to set, especially in the case of a thick head of hair which is often dry, dull, rough or lacks vigor and liveliness.
Efforts heretofore have been made to limit or to correct these faults by applying to the hair a "hair conditioner" composition so as to improve the condition of moist and dry hair and to facilitate such operations as combing and setting the hair.
By "Hair conditioning" is meant an operation which, while facilitating the combing out of moist hair, also imparts to dry hair some swelling and elasticity, so as to assure good maintenance of the coiffure or style imparted thereto. The agents employed to achieve such "hair conditioning" are generally called "hair conditioners".
Conventionally there are employed in the conditioning of hair various synthetic polymers, such as polyethylene imines, polyvinylpyridines, the polychloride of p-vinylbenzyl trimethylammonium and the polychloride of diallyl dimethyl ammonium. However, it has also been found that these polymers suffer from the disadvantages of not being compatible with, for instance, anionic shampoo compositions.
It has also been known to use in the production of compositions for hair some polyamino-amide polymers, obtained by the polycondensation of a dicarboxylic acid and a polyalkylene polyamine, some polyaminoureylene polymers and some alkylene polyamine polymers modified particularly by epichlorohydrin in quantities near stoichiometric amounts relative to the amine groups of the polyamino-amide. However, the addition of these significant quantities of epichlorohydrin leads to the presence in the molecules of the crosslinked polymer some reactive groups. These polymers thus contain alkylating groups which are capable of reacting on nucleophilic groups such as amines, thiols, sulfates and the like. Representative of such alkylating groups are azetidinium rings. However, as a result of the presence of such reactive groups, the polymer lacks stability and generally degrades when put into solution. Further the presence of such alkylating groups renders cosmetic products incorporating the same of doubtful use for application to human skin.
There has also been recommended the use in a "hair conditioner" composition of heat crosslinkable thermosetting polymers, but their use necessarily involves a special heating step.
To avoid these drawbacks, there has been provided in our earlier applications Ser. Nos. 762,804 and 528,577, incorporated herein by reference, a chemically stable, crosslinked polyamino-polyamide free from reactive groups. This water-soluble crosslinked polymer is obtained by crosslinking a polyamino-polyamide which in turn is prepared by the polycondensation of an acidic compound on a polyamine. The acidic compound used is selected from the group consisting of:
(i) an organic dicarboxylic acid, PA1 (ii) an ethylenically unsaturated aliphatic mono- or di-carboxylic acid, PA1 (iii) an ester of said acids, preferably with a lower alkanol having from 1-6 carbon atoms, and PA1 (iv) mixtures of these compounds.
The polyamine usefully employed to produce the polyamino-polyamide of our earlier applications is selected from the group consisting of bis-primary and mono- or bis-secondary polyalkylene-polyamines. From 0-40 mole percent of the selected polyamine can be replaced by a bis-primary amine, preferably, ethylenediamine or by a bis-secondary amine, preferably piperazine and 0-20 mole percent of the selected polyamine can be replaced by hexamethylene-diamine.
Crosslinking of the polyamino-polyamide in our earlier applications is effected with a crosslinking agent selected from the group consisting of epihalohydrins, diepoxides, dianhydrides, unsaturated anhydride and bis unsaturated derivatives, and is characterized by the fact that the crosslinking agent is employed in amounts of 0.025-0.35 mole of crosslinking agent per amine group of the polyamino-polyamide and generally from 0.025 up to about 0.2 mole and, in particular, from 0.025 to up to about 0.1 mole of crosslinking agent per amine group of the polyamino-polyamide.
Our earlier invention, as described in said Ser. Nos. 762,804 and 528,577 is also concerned with a hair conditioning cosmetic composition which comprises at least one water-soluble crosslinked polymer as defined above. This cosmetic composition is compatible with anionic shampoo compositions; it provides satisfactory combing out of moist hair and it imparts elasticity to dry hair thereby assuring good maintenance of the coiffure or style imparted to the hair.
The crosslinked polyamino-polyamidde present in the hair conditioning composition of our earlier invention exhibits the following characteristics: (1) it is perfectly soluble in water up to 10 water percent concentration without forming a gel; (2) the viscosity of such a 10% solution in water at 25.degree. C. is greater than 3 centipoises, the viscosity generally measuring between 3-200. More often the viscosity of such a solution is equal to or greater than 20 centipoises and lower than 50 centipoises; and (3) the polyamino-polyamide does not carry any reactive group and in particular it is chemically stable and does not have any alkylating characteristics.